Monoterpenoid Indole Alkaloids from Alstonia yunnanensis

Eight new monoterpenoid indole alkaloids, alstoyunines A-H (1-8), along with 17 known analogues, were isolated from Alstonia yunnanensis. The structures of. the new alkaloids were established by means of extensive spectroscopic methods. Alstoyunines C (3), E (5), and F (6) showed selective inhibition of Cox-2 (>75%). Alstoyunine F (6) showed weak cytotoxicity against the human myeloid leukemia HL-60 (IC50 = 3.89 mu M) and hepatocellular carcinoma SMMC-7721 (IC50 = 21.73 mu M) cell lines.